Lubricating device for chain saws



Sept. 14, 1954 D. J. SMITH LUBRICATING DEVICE FOR CHAIN SAWS Filed April 17, 1951 INVENTOR DONALD J. SMITH @wa 7Zw% ATTORNEY Patented Sept. 14, 1954 UNITED STATES ATENT OFFICE LUBRICATING DEVICE FOR CHAIN SAWS "Application April 17, 1951, Serial No; 221,370

. 4-Glaims.

l The present invention relates to power-driven chain saws of the type in which a chain-composed of pivotally connected cuttinglinks is driven around a cutterbarby amotor, such as an internal combustion engine, or amotor receivingits energyfrom a source of fluid-pressure, or electrical power.

The object of'the present invention is to pro- 'Vide a lubricating device'for a chainsaw of the above indicated type that will insureithe delivery of a supply of lubricant to the links ofthe chain saw, every time that the saw isengaged with a log, or other-piece of work, preparatory to making .a cut therein. Briefly stated-, -the-invention resides in providing the -flame-of a chain saw with a lubricant supply and a reciprocating pump, operable by an external plunger-'slidably appear from the following description, considered in connection with the accompanying drawings, inwhich,

Fig. 1 Ba view in sideelevationof apowerdriven chain saw provided with alubricatingdevice incorporating the present invention.

Fig. 2 is a view in elevation of the opposite side of the saw shown in Fig. i.

Fig. 3 is afragmentaryview-partially inside elevation, and partially in section, showing-the lubricating device of Fig. 1 on an-enlarged scale.

Fig. 4 is a vertical-sectionalviewalong the line 44 of Fig. 3, looking-in the directionof-the arrows. c

Fig. 5 'is a viewin vertical section along-the lineE-IB of Fig. 3, looking in the 'direction'of the :arrows.

Referring first to Fig. 1, the inventionisshown for purposes of illustrationas being embodied in a power-driven chain saw in which the-chain'C consists of cutting links -I 'pivotally connected together, and supported "for slidingmovement around the edge of arigid cutterbar 2. The inner end of thebar 2 is mounted on a'frame 3 and the chain C is driven by means of a sprocket mounted on'a shaft 5, see Fig.2,which shaft is driven from a suitable motor M, s0 that'the chain C ridesaround the outside of the bar 2, with "the cutter links I on the underside of the chain movingtowards the right.

One side of the frame 3 provides a projecting bumper 5 facing in the'directicnsof-the cutter'bar 2, the purpose of the bumper 6 being to engagethe logyor other work, which is to be cut by the underside of the moving chain, as viewed in Fig. 1. The outline of a log L is indicated'in dot and dash lines in Fig. .1, and it is obvious that as the cutter links I of the chain C enter the upper-surface of the log to make a cut,

the direction of movement of the chain, is such as to press the log L against the bumper 8 at'the very start of the cutting operation. In other words, the cutting action of the chain 0 will always tend to draw together the 'bumper 6 and the surface of the log below the zone of cutting, and this relative movement between the saw frame and the work being cut,-is depended upon to operate-the lubricating device which constitutes the present invention.

Referring now to Figs. 3 and 4, a portion of the frame 3 and the bumper 6 is-shown on an enlargedscale,- andit-will be seen that the lower portion of the frame is provided with. a cylinder 1' which is shown in section. The .cylinder 1 provides a bore 8 within which a piston 9 is movable, witha spring It tending to yieldingly maintain the piston 9 at the'right-hand end of the cylinder 1. A rod l l is connected to the piston 9 and extends through a suitable packing ring I2 into an opening l3, provided inthe lower portion ofthe bumper 6.

The outer end ofthe pistonrod li-carries a shoe l t'which asbest shown in Fig. 5 :extends through a slot 15 provided'in the front face of the bumper 6. The shoe is is freely movable in the slot Land the pressure of the spring ii} on thepiston 9 is such as to normally maintain the shoeldwith its major portion projecting beyond the-face of the bumper 6. .Therefora'it .will be apparent from a consideration of Fig. .1 that Whenever'the cutter links I of thechain 1C engage the log L, at the'start of a cut, the pull of the moving chain will engage the end of the shoe I l with the surface of the log, as a result of which the shoe will be forced inwardly through the bumper slot E5 to move the piston 9 to the left against the pressure of the spring [0.

For the purpose of supplying the cylinder 1 with lubricant, such as oil, a tank I6 is mounted on one side of the frame 3 above the cylinder I. The bottom of the tank It provides an opening ifia for receiving a valve [1, from which extends a pipe l8. As best shown in Fig. 4, the pipe l8 passes behind the end of cylinder 1 and is bent around so as to enter an oil storage reservoir I9 forming part of the pump cylinder i. This reservoir i9 is closed by a plate extending along one side of the cylinder 1, and pipe I8 is received in a fitting 2! provided by the plate 20. The reservoir I 9 is in continuous communication with the bore 8 of thecylinder I through a port 22. l

As best shown in Fig. 3, the port 22 enters the cylinder bore 8 at a point just beyond the lefthand end of the piston 9 when the latter occupies its normal position, in which the shoe H5 is yieldingly held beyondthe face of the bumper 6 by the pressure of the spring l0. Therefore, when the valve I? is open, oil from the tank Hi can flow freely through the pipe 18 into the reservoir I9 from which it enters the cylinder bore 8 through the port 22. As a result, the cylinder bore 8 is kept filled with oil in readiness for a pumping operation as long as the shoe It remains in the full line position of Fig. 3.

The end of the cylinder 7 opposite to the piston 9 provides a discharge port 23 for receiving a fitting 24 from which a pipe 25 leads to a second fitting 26 extending through an opening 21 provided in the bumper 6. This opening 2'! extends through to the cutter bar 2 and is in communication with a passage 28 leading to the edge of the cutter bar 2 around which the chain C passes. The passage 28 is indicated in dotted lines in Fig. 1, from which it will be apparent that oil delivered under pressure to the pipe 25 from the pump cylinder 1 will be conducted directly to the cutter .bar 2 at a point where the chain C travels after leaving the driving sprocket 4.

From the foregoing description of the construction of the pump and the arrangement of the pipe connections between the oil tank It, the cylinder bore 8 and the cutter bar 2, it will be apparent that inward movement of the shoe I l, as a result of its forceable engagement with the surface of a log L, will cause the piston 9 tomove inwardly against the spring Ill and thereby force the oil in the bore 8 under pressure through the pipe 25 to Where it will lubricate the cutter links I of the saw chain C. Since the shoe M is forced inwardly at the very start of a cut in the log by the chain saw, the resulting operation of the pump will insure that the chain will be thoroughly lubricated as the cutting progresses. Furthermore, upon each withdrawal of the cutter bar 2 from the log in preparation for a new out, the spring [0 will again force the piston 9 to the right, as viewed in Fig. 3, and thereby again project the shoe M beyond the face of the bumper 6. Whenever this occurs, oil from the reservoir [9 is free to enter the cylinder bore 8 through the port 22 in response tothe suction created by the movement of piston 9, so that the bore is full of oil in readiness for delivery to the cutter bar 2 through the pipe 25 when the shoe I4 is again pressed into the bump- 4 er 6, upon engagement with the surface of the log L.

From the foregoing, it is apparent that by the present invention there is provided an improved lubricating device for power-driven chain saws that is characterized by its simplicity of construction and effectiveness in operation. As a result of providing a pump that is operable only in response to engagement with a log at the beginning of a cut, the consumption of oil is reduced to a minimum. This is an important factor in woods operations, wherein the intermittent use of the saw for actual cutting requires running of the driving motor for considerable periods when it is disconnected from the chain saw. During such periods, the pump of the present arrangement is not operating, which would not be the case were the pump to be driven from the motor. While the reservoir it; contains sufficient oil to supply the cylinder bore 8 at all times, there is no delivery of oil by the pump until the saw is actually engaged with the work; consequently the oil consumption of the pump is determined by the number of cutting operations performed by the saw, over any given period.

I claim: 1. A chain saw and lubricating device thereforecomprising in combination, a frame, a chain saw movable with respect to said frame, a bumper on said frame for engaging a piece of work, while being cut by said saw, a supply of lubricant carried by said frame, a pump mounted on said frame, and connections between said lubricant supply, pump and chain saw, said pump having an operating plunger extending through said bumper and terminating in a shoe projecting beyond the work-engaging face of said bumper for engagement'by the work, whereby to deliver lubricant under pressure from said supply to said saw. 2. A chain saw and lubricating device therefor comprising in combination, a frame, a cutter bar extending from said frame, a chain saw driven around said cutter bar by a motor on said frame, with said cutter bar providing a passage leading to said saw, a bumper on said frame for engaging a piece'of ,work being'cut by said saw, a lubricant tank on said frame, a pump mounted on said frame below said tank, connections between said tank, pump, and cutter bar passage, and a plunger extending from said pump through said bumper carrying a shoe at its outer end. which projects beyond the bumper for engagement by a piece of work, to thereby operate said plunger and cause said pump to deliver lubricant under pressure to said cutter bar passage. 3. A chain saw and lubricating device therefor comprising in combination, a frame, a cutter bar extending from said frame, a chain saw driven around said cutter bar by a motor on said frame, a bumper on said frame for engaging a piece of work being cut by said saw, a lubricant tank on said frame, a pump mounted on said frame below said tank, connections between said tank, pump, and cutter bar, a plunger extending from said pump through said bumper, and a spring acting on said plunger for yieldingly maintaining the outer end of said plunger beyond the work-engaging face of said bumper, for engagement by a piece of work at the start of a cut therein by said saw, to thereby operate said pump.

4. A chain saw and lubricating device therefor comprising in combination, a frame, a chain saw slidably mounted with respect to said frame, a bumper on said frame for engaging a piece of work while being cut by said saw, a supply of lubricant carried by said frame, a cylinder mounted on said frame with its axis parallel to the direction of movement of said saw as it engages the work, connections between said lubricant supply, cylinder and saw, a piston movable in said cylinder and having an extension movable in said bumper, and a spring operable on 10 said piston for yieldingly maintaining the outer end of the piston extension beyond the workengaging face of said bumper with said cylinder full of lubricant, whereby engagement of the piston extension by a piece of work at the start of 15 a cut therein by said saw serves to displace said piston and deliver lubricant to said saw through one of said connections.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 764,886 Donnenwerth July 12, 1904 882,318 Howe Mar. 17, 1908 1,903,571 Meyer Apr. 11, 1933 FOREIGN PATENTS Number Country Date 221,659 Switzerland Aug. 17, 1942 

